Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds genuinely behavioral context the annotations cannot: routes are single-state and terminate at the state line, stops are filtered against dog weight and the pet-fee budget, and California vs. Nevada mile conventions differ. It does not discuss result volume or what happens when a start point is off-route, which is why this is a 4 rather than a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose and constraints are front-loaded and the worked examples earn their space. But the 'Routes covered:' inventory largely restates the route enum already present in the schema, adding only mile lengths, and the prose paragraph above it covers much of the same ground — roughly a third of the text is redundant with structured data.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 14-parameter tool with a nested `near` object and an output schema, this description supplies what structured data cannot: the mile/direction model, per-route jurisdictions, and the filtering semantics for weight and fees. Nothing an agent needs in order to construct a correct call is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline would be 3, but the description goes well beyond it: it explains that direction means increasing miles (north/east), that California miles follow the Caltrans odometer from named origins while Nevada counts mileposts from the state line, and that on_road marks Highway 1 stretches running on US-101. That is interpretation an agent cannot derive from the schema alone.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource ('Dog-friendly stops along a California or Nevada highway, in driving order') and enumerates exactly which kinds of stops are included, plus the alias relationship to dogpolicies_route_stops. An agent can tell this apart from dogpolicies_near or dogpolicies_plan_trip without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It names the alias condition ('kept for older clients') and states a hard usage requirement: 'Give a starting point with from_mile or near, and a direction.' Five worked examples map natural-language requests to concrete argument sets. It does not, however, say when to prefer this over dogpolicies_plan_trip or dogpolicies_near, which the sibling list makes plausible alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.